. >> i would like to see some details both from romney and obama mainly on tax policy. >> reporter: vice president biden charged today, team romney would hike middle class taxes. >> how they can justify raising taxes of the middle class that has been buried the last four years. >> reporter: the republicans jumped on that. buried by obama? in colorado, mitt romney took a break for a burrito bowl. >> how are you doing today? >> reporter: romney's number two, paul ryan, kept campaigning. >> the obama economic agenda failed not because it was stopped. it failed because it was passed. >> reporter: that's the kind of zinger sure to be heard tomorrow night. doug, andrew and chris say they hope to hear a lot of substance, too. a debate number one in their battleground state. >> reporter: so how critical will this first presidential debate be? today's nbc news "wall street journal" poll finds 38%, more than a third of voters say this debate and the ones to follow will be quite important or extremely important to their decision about who to vote for. live from denver, i'm steve handelsman, news 4.